This invention relates to an image output apparatus and method capable of outputting ordinary page data and form data, for example, in an overlaid state.
Ordinary business activities often require the printing of documents in which standard form data and non-standard data are superposed. The standard form data (titles and border lines), such as slips and standard documents, has the same content over a plurality of pages. The non-standard data (such as numerals and names, referred to as xe2x80x9cordinary page dataxe2x80x9d below) has content that differs on every page. Form overlay printing often is used to achieve printing of the type described.
In a conventional page printer in which print data described in page description language is analyzed and a raster image corresponding to the description is generated, form data described in the page description language is registered in the storage area of a printer as an event-driven macro instruction and the macro instruction is executed automatically in response to an event such as a paper discharge operation to implement form overlay printing. When the macro instruction is registered and when, say, a paper discharge instruction is received following the analysis of one page of ordinary page data, the registered content is read out, analyzed in the same manner as ordinary page data and converted to an intermediate code for generating one page of a raster image. An intermediate code generated from data described in page description language will be referred to as a drawing object below. A dot image that expresses a single character pattern is one example of a drawing object. An operation that uses drawing objects to generate image data in units of pages or bands is referred to as xe2x80x9cdrawingxe2x80x9d. Further, registering form data in a printer is referred to as xe2x80x9cform registrationxe2x80x9d. Form registration is carried out by a form registration instruction having a predetermined format.
A printing system that is available is adapted to transfer form data (a macro instruction) from a host computer to a printer before printing is executed, and to register the form data in a non-volatile memory such as a flash memory so that the form data need not be transferred each time. In such case only the instruction which specifies the form data in the flash memory as the event-driven macro is sent when printing is executed.
The problems set forth below, however, are encountered with the example of the prior art described above. Specifically, in a case where form overlay printing is implemented by an event-driven macro, the form data is described in the format of page description language. If the form data is complicated, therefore, the analysis of the form data per se and the generation of a drawing object take time. That is, in regard to output of the first page, the processing speed achievable is only equivalent to that obtained when a document containing a form is output as ordinary data without using overlaying. The more complicated the content of the form, the longer the time needed to process the form.
When print data in which the same form is used over a plurality of pages is output, the same macro instruction (command group) is analyzed and the same drawing objects are generated each time on a page-by-page basis. Consequently, printing speed from the second page onward cannot be raised regardless of the fact that forms of identical content are output. More specifically, the same drawing objects are generated for every page, i.e., a single drawing object cannot be shared by a plurality of pages. This means that the memory necessary for processing to draw a plurality of pages must be large in size, and there is the danger of a decline in performance as when waiting for paper discharge. In particular, when a complicated form containing figures and pictorial images is specified for overlay printing, errors such as inadequate image memory tend to occur. Thus, a solution to the above-mentioned problems is vital.
One solution that has been considered is to rasterize the form data in advance, store the rasterized data in a printer as image data (a form image) and draw the image data in a state in which it is superimposed on the ordinary page data. However, this is impractical as a large-capacity memory is necessary to hold one page of a form image. To be specific, a memory having a storage capacity of about 8 MB would be required to store a size-A4 monochrome image at a resolution of 600 dpi.
Further, if a form image is generated in regard to a form composed of simple straight lines or the like, the result would be a decline in the processing speed of one page and a decline in memory efficiency.
The present invention is made in consideration of the above problems and has as its objects to suppress an increase in the processing time in the forming unit even if the contents of the form is complicated. Furthermore, another object of the present invention is to increase the printing speed after the first page in a case where a form having the same contents is repeatedly printed. Furthermore, still another object of the present invention is to provide an image output apparatus and method which can suppress an increase in a necessary memory for rendering process of a plurality of pages.
In order to achieve the above object, according to the present invention, the image output apparatus comprises form storage means for encoding and storing form data generated as image data form generating means for generating form data as image data, encoding the form data and storing it in the form storage means and overlay output means for decoding the encoded form data that has been stored in the form storage means, superposing print data on the decoded form data and outputting the result in a case where the print data is to be output upon being overlaid on the form data.
In order to achieve the above object, according to the present invention, the image output method comprises a form generating step of generating form data as image data, encoding the form data and storing it in form storage means and an overlay output step of decoding the encoded form data that has been stored, superposing print data on the decoded form data and outputting the result in a case where the print data is to be output upon being overlaid on the form data.
In order to achieve the above object, according to the present invention, the computer-readable memory stores a program which causes a computer to implement the functions of form generating means for generating form data as image data, encoding the form data and storing it in form storage means and overlay output means for decoding the encoded form data that has been stored, superposing print data on the decoded form data and outputting the result in a case where the print data is to be output upon being overlaid on the form data.
In order to achieve the above object, according to the present invention, the image output system comprises a host apparatus for converting print data to a print instruction having a format in which it can be interpreted by a printing apparatus, outputting the print instruction, combining form data with print data and outputting the result and a printing apparatus for interpreting the print instruction output by said host apparatus and converting the print instruction to an image the host apparatus having means for measuring degree of complexity for each type of print data and means for instructing the printing apparatus to execute an encoding procedure that conforms to the degree of complexity measured and the printing apparatus encodes or decodes form data using the encoding procedure instructed.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.